Automatic control mechanism for grading apparatus



Dec. 27, 1960 D. D. COLEE 2,

AUTOMATIC CONTROL MECHANISM FOR GRADING APPARATUS Filed July 13, 1956 2 Sheets-Sheet 1 v INVENTOR.

.DONALD ,0. 51.55,

firming D 2 19 0 D. D. COLEE 2,965,990

AUTOMATIC CONTROL MECHANISM FOR GRADING APPARATUS Filed July 15, 1956 2 Sheets-Sheet 2 ,DaA/4LD D- 65455,

INVENTOR.

United States Patent AUTOMATIC CONTROL MECHANISM FOR GRADING APPARATUS Donald D. Colee, Phoenix, Ariz., assignor to Preco Incorporated, Los Angeles, Calif., a corporation of California Filed July 13, 1956, Ser. No. 597,674

13 Claims. (Cl. 37-156) The present invention represents certain improvements of the blade control apparatus disclosed in my prior application Serial No. 498,983, now Patent No. 2,904,911, entitled, Gyroscopic Control Mechanism for Grading Apparatus, in which apparatus for controlling the special position of an earth working blade was disclosed. In

particular, theimprovements are directed to such automatic position control of the earth working blade in relation to the vehicle and to a plane extending in the direction of vehicle advancement that the blade may be very accurately positioned by operating a remote control, and further that the blade may be maintained at accurately controlled depth relative to the vehicle and at controlled inclination relative to such a plane without disturbance even though the vehicle travels over undulating or variably sloped portions of the ground as during the course of grading a road over the hump of a hill. 7

The particular problem solved by the present invention concerns automatic control of a road grader blade during.

the course of continuous grading of roads or shoulders the slope of which varies with the terrain over which the grader travels, and it will be seen during the discussion to follow that automatic controls having partic ular controlling effect on the grading blade should be. utilized to achieve the desired accuracy of grade control.v

In accordance with the invention, there is provided a remote auxiliary control movable by the operator to selected reference positions matching different desired tool positions, together with means controlling the tool through a power system in response to mismatch between a particular selected control position and thecorresponding tool position to' displace the tool to the selected or desired position. The remote control or controls may govern tool depth relative to the vehicle or tool inclination relative to a plane extending in the direction of vehicle advancement, or both, and the means controlling tool position in response to the remote control may operate through an existing manual control for the power system, adapting the present control system for use in combination with existing road graders or other earth working equipment. 7

With respect to the control of both depth and inclination of the grader blade, the invention contemplates the use of a potentiometer bridge circuit in which one potentiorneter is operated by the remote control and the other by depthwise or inclinationwise displacement of the blade, 7

to produce bridge unbalance and a resulting error signal effective to displace the blade to a particular depth or inice clination corresponding to the position of the remote control. As a result the operator need only move the calibrated remote control to a particular position in order to very accurately set the position of the blade as regards its depth or inclination. As respects inclination control,

. blade inclination sensitive means in the form of a gyroscope is provided in controlling relation with one of the otentiometers in the bridge so that, as lateral inclination of the vehicle changes, the bridge will become unbalanced and the blade will be correspondingly tilted to balance the bridge through displacement of the potentiometer operated by the gyroscope.

Other features and objects of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

Fig. 1 is an elevation showing the complete road grader;

Fig. 2 is an enlarged plan view of portions of the grader;

Fig. 3 is an enlarged elevation of the forward portion of thegrader;

Fig. 4 is a section taken on line 44 of Fig. 3;

Fig. 5 is a section taken on line 5-5 of Fig. 3;

Fig. 6 is a circuit diagram' showing circuit elements used for controlling the position of a grader blade;

Figs. 7 and 8 are enlarged views of the remote controls shown in Fig. 2; and

Fig. 9 is a perspective view of the gyroscope used for controlling blade inclination. H 1 I Referring generally to Figs. 1 through 4,. the road grader 10 is shown to comprise an engine-driven wheeled portion of the frame 12 between the wheeled vehicle 11 and the forward wheel 13 is angled upwardly relative to ground level 19 over which the grader is movable, in

order that the blade 20 may be suspended beneath the frame for various movements relative to the frame as will be described.

The blade itself is cylindrically curved transversely of its length, presentingits concave face relatively forwardly: "and terminating in a blade edge 2.1 variably engageable' with the ground. A ring-shaped circle 22 shown extend'-' ing in a horizontal plane spaced above the ground in Figs. 1 through 4 carries the blade .for rotating it about" a vertical axis to establish desired blade angularity with r'espectto the direction of vehicle advancement, circle rotation being eflfected by manually controlled shafting 23 turning a gear 24 engageable with the toothedinner diameter of the circle. The latter is hung beneath sup-I porting draw bar 25 in the form of an A-frame and u beneath cross member 26 connected with the legs of the draw bar. Forward pull is transmitted to the draw bar from the frame 12 through a universal pivotconnection 27 accommodating up and down pivoting and lateralirrclination of the draw bar and blade with respect to the],

frame and the forward wheel. Therefore, rotation ofjthe circle v22 by gear 24 is not always about a vertical axisbut may be characterized as being about an axis extending'upward but at an angle from the vertical depending upon the patricular angular inclination of the circle and blade and their disposition with respect to the universal pivot 27.

The blade is movable to diiferent positions by the operator at the platform 16 through the manipulationjof 1 appropriate right. and lefthand toggle levers 29 projectijn'gf upward from the control panel 28, right and lefthand" 3 levers 29 being suitably connected in controlling relation with motor units operative to raise, lower and tilt the blade relative to the frame as will be described, raising and lowering being accomplished by forward and rearward displacement of both the levers whereas tilting is effected by relatively opposite forward and rearward displacement of the two levers.

Referring to Figs. 2 through 4, the position of the circle 22 and blade 20 is controlled by power actuating mechanisms, including a pair of rotatable lifting shafts 31 connected to the motor units 30 for rotation separately or together and in opposite or similar directions in accordance with the positions of the right and lefthand control levers 29. The forward ends of the shafts are journalled in laterally extending frame supports 32 and connected to lifting cranks 33. The latter suspend lifting links 34 at opposite sides of the frame 12 through joints 35, the links in turn supporting the cross member 26 through joints 36. From an inspection of Figs. 3 and 4 it is clear that like lifting or lowering of the links 34 effects lifting or lowering of the blade, whereas opposite lifting and lowering of the links inclines the blade and circle in the plane through the lifting links.

Referring now to Fig. 2, remote auxiliary controls 37 and 38 are attached at the side of the control panel 28 to be accessible to the operator, the controls respectively referencing inclination of the blade in the transverse plane of the lifting links or with respect to a plane extending in the direction of vehicle advancement, and blade depth relative to the forward wheel, 13. Each of the controls is shown in Figs. 7 and 8 to include a knob 39 carrying a pointer 40 rotatable by the knob to reference positions with respect to calibrated dial 41 indicating roll or angle of the blade in degrees and percent ofslope on control 37, and indicating blade depth gradations. in tenths of feet and quarter tenths of feet on control 38.. Movements of the blade inclination and depth control knobs respectively displace the taps 42 of potentiometers 43 and 44 shown in Fig. 6, suitable potentiometers being conveniently associated with the control knobs 39 as is well-known. Other potentiometers 45 and 46 are electrically connected respectively with potentiometers 43 and 44 to provide two potentiometer bridge circuits energized by batteries 47 when the switches 48, conveniently located at the sides of the controls, are closed. The tap of each potentiometer taps from the winding a voltage which depends in a definite manner upon the position of the tap and which may be described asan electricaloutput representing that position. Each bridge is in balance when the outputs from its two potentiometers are equal.

Reference will now be made to the connections and mechanisms operable to actuate or change the settings of the potentiometers 45 and 46, these elements forming a, means for detecting the position. of the blade. Potentiometer 46 is shown in Fig. to include a slide wire 147 mounted in a case 48 carried by link 49, and a tap 50 rotatable in contact with the slide wire by a gear 51 meshing with a segment 52 carried by arm 53. The latter is supported from the forward frame end 14, and in turn supports one end of link 49 by a pivot connection 54 so that upward and downward pivoting of the link effects actuation of the potentiometer 46 through the gear and segment. A connecting link 55 interconnects the draw bar 25, at pivot 55a with link 49 for transmitting to thelatter up and down movement of the draw bar relative to the forward wheel- 13. Drag link 49 and link 55 thus form a linkage mechanism that is deflected in responsecorresponds to the vertical swinging movement of the described axis relative to frame 12, and is independent of draw bar rotation about that axis.

Potentiometer 45 is shown in Fig. 9 to include a slide wire 56 and a tap 57 rotatable by tilting of a gyroscope 58 with respect to its cage 59. Cage 59 serves as support means for the gyroscope and potentiometer 45 within housing 60. The gyroscope housing 60 is centrally connected to the front of the cross member 26 as shown in Figs. 2 through 4 so that it remainsforwardly oriented at all times insofar as the draw bar and cross member are so oriented. The cage 59, however, turns with the circle 22 to orient the cage and gyroscope with the circle and relative to the draw bar. A shown in Figs. 2 through 4, the connection between gyroscope cage 59 and circle 22 includes a shaft 61 projecting downward from the cage 59 through a bearing 62, and a horizontal link 63 connected with the lower end of shaft 61 to project forwardly through a sleeve 64 hung from the circle. Therefore, as the circle rotates about a vertical axis, the gyroscope and cage are turned with the circle, any take-up being accommodated by the sliding fit of the link 63 and sleeve 64. As a result of this arrangement, the electrical output of the potentiometer 45 accurately indicates the degree of tilting or inclination of the blade edge even though the gyroscope and potentiometer are not directly mounted on the blade.

Referring again to Fig. 6, each potentiometer bridge includes a very sensitive relay 65 including a single pole double throw switch 66 which closes in response to the fiow of current through the potentiometer taps when the bridge is electrically unbalanced. Eight power relays 67 are inturn variously operated by the bridge relays as shown in the, circuit diagram for the purpose of connecting the electrical power source 68 with the four solenoids 69. Those solenoids control the right and lefthand toggle levers 29 through the armature units 74. The solenoids are connected in pairs, each pair controlling one armature unit and its associated toggle lever through electrical energization of one or the other solenoid of the pair to urge the lever forward or backward respectively. Each pair of solenoids may be referred to as a solenoid means. The mechanism which thus actuates each of the manual controls 29 may be referred to for convenience as an actuator.

Tracing through the operation of the toggle levers 29 in response to bridge unbalance, when the inclination control 37 is operated by turning its knob 39 to a selected reference position corresponding to a selected blade inclination, tap 42 of potentiometer 43 is thereby moved to selected position normally resulting in electrical unbalance of the potentiometer bridge controlling blade inclination, and electrical current then flows through taps, 42 and 57 to energize relay 65 sending current through lines 70- or 71 depending'upon the direction of relay actuation. Assuming current flows through line 70, relays 67a and 67b are actuated to energize solenoids 69a and 69d, resulting in relatively opposite or differential displacement of the right and. left-hand toggle levers 29. Accordingly, the blade 20.and circle frame are tilted, carrying with them gyroscope housing 60 and cage 59. As, is clear from Fig. 9, winding 56 of potentiometer 45is carried along with the tilting movement of cage 59, whereas tap 57 is held stationary in space by action of the gyroscope. The resulting movement of tap 57 over the potentiometer winding. tends to restore balance of the bridge. The described opposite displacement of toggle levers 29 causing tilting movement of blade 20 to continue until the tap- 57 moves along slide wire 56 far enough to rebalance the bridge. Likewise, the blade may be tilted in the opposite direction through energization of solenoids 69b and 69c viarelays. 67c and 67d.

Referring now to control of blade depth, when the remote control 38 is manipulated by turning its. knob 39 to selectedreference position corresponding; to desired blade depth, tap 42 of potentiometer 44 is moved to unbalance the other bridge circuit sending current through taps 42. and 50 to energize its relay 65. Assuming current is then caused to flow through line 72, relays 67a and 67 are actuated to energize solenoids 69a and 69c, resulting in displacement of right and lefthand control levers 29 in the same direction. The blade is then raised, causing link 49 to swing about its pivot 54 and moving tap 50 over the slide wire 147 of potentiometer 46. That blade movement continues until the bridge is balanced. Similarly, current sent through line 73 as a result of reverse actuation of relay 65 effects energization of solenoids 69b and 69a through actuation of relays 67g and 67h to lower the blade.

From the foregoing it is apparent that the depth and inclination positions of the lade 20 may be extremely accurately controlled merely by operating the remote controls 37 and 38, and it has been found in practice that the depth location of the blade may be held within one quarter of one-tenth of a foot. Similarly, the angularly of the blade may be very accurately controlled. Should the grader during the course of its operation advance over terrain having different slopes in the direction of advancement, the depth of the blade relative to the forward wheel 13 does not change but remains accurately located relative to the wheel. Should the grader frame 12 tilt sideways, however, tending to tilt the blade with the frame, the gyroscope 58 displaces thetap 57 of potentiometer 45 to unbalance its bridge and thereby effect energization of the solenoids and displacement of the control levers 29 causing opposite tilting of the blade. That blade movement continues until tap-57 of potentiometer 45 is returned to its initial position, rebalancing the bridge. That action thus maintains the blade at the selected angle of inclination relative to a plane extending in the direciton of vehicle advancement. Should the operator desire to operate the blade independently of the automatic controls described above, he need only throw the switches 48 to de-energize the bridge circuits as shown in Fig. 6.

I claim:

I In a road grader, the combination of a forward frame assembly and a forward ground engaging wheel supporting the assembly for advancement over the ground, said assembly including frame means rearward of the forward wheel and movable up and down relative thereto, said frame means including a drag link pivotally connected with a part of the frame assembly that is movable up and down with the forward wheel, an earth working blade carried by said frame means for blade edge travel in a selected plane during grader advancemerit, power actuated means connected with said frame means for displacing the blade, said power actuated means including twolifting mechanisms connected with said frame means at laterally spaced locations, a pair of manually actuatable controls connected with said power actuated means for controlling lifting and lowering of said frame means at said locations respectively, an auxiliary control movable to different positions matching different blade positions, and means operatively connected with said frame means controlling said power actuated means through said manual controls in response to mismatch between selected auxiliary control position and blade position to displace the blade to selected position, said last named means including a pair of actuators respectively connected with said manual controls and a pair of potentiometers electrically interconnected in a bridge controlling both said actuators, said potentiometers being actuatable in response to said movement of the frame means and of said auxiliary control, respectively, one of said potentiometers being operatively connected with said drag link and with said part of the frame assembly.

2. The invention as defined in claim 1 in which said frame means and blade are inclinable by said power actuated means, a second auxiliary control movable to different positions matching different blade inclinations, and in which said means controlling the power actuated means includes means sensitive to blade inclination and another pair of potentiometers connected in a second bridge controlling both said actuators, said potentiometers being respectively actuable in response to changes in said blade inclination and movement of the second auxiliary control.

3. The invention as defined in claim 2 in which said means sensitive to blade inclination comprism a gyro-v scope wheel.

4. The invention as defined in claim 3, including a gyroscope cage supporting said gyroscope wheel and mounted for rotation about a substantially vertical axis, and in which said frame means includes a blade support operatively connected with the gyroscope cage to rotate it with the support about a substantially vertical axis.

5. The invention as defined in claim 1 in which said actuators include solenoids for displacing said manual controls in response to electrical unbalance of said bridge.

6. The invention as defined in claim 1 including a carrier connected with said drag link and frame assembly part and having portions relatively movable in response to up and down pivoting of said drag link relative to said frame assembly part, and in which said one potentiometer is carried by said carrier and actuable in response to said relative movement of said carrier portions.

7. A control system for positioning the blade of a grading machine which comprises a vehicle frame, a draw bar pivotally mounted at its forward end on the vehicle frame for angular movements relative thereto in'respective'longitudinal' and transverse planes, a circle frame carrie'd rot'atably on the draw bar and rotatable with 35 respect thereto about a circle axis, a grading blade carried by the circle frame and power means actuable to drive the draw bar in its transverse movement to vary the inclination of the blade; said control system comprising the combination of support means, bearing structure supporting the support means on the draw bar independently of the circle frame for rotation relative to the drawbar about an axis parallel to the circle axis, coupling means connected between the support means and the circle frame for driving the support means in its said rotation, sensing means mounted on the support means and responsive to changes .of inclination thereof, and means for actuating said power means under control of the sensing means.

8. A control system for positioning the blade of a grading machine which comprises a vehicle frame, a draw bar pivotally mounted at its forward end on the vehicle frame for angular movements relative thereto in respective longitudinal and transverse planes, a circle frame carried rotatably on the draw bar and rotatable with respect thereto about a circle axis, a grading blade carried by the circle frame and power means actuable to drive the draw bar in its transverse movement to vary the inclination of the blade; said control system comprising the combination of structure fixedly mounted on the draw bar and forming a housing, shaft means journaled on an axis parallel to the circle axis and extending through a wall of the housing, means for driving the shaft means from the circle frame, sensing means mounted on the shaft means within the housing and responsive to changes of inclination of the shaft, and means for actuating said power means under control of the sensing means.

9. A control system as defined in claim 8, and in which said means for driving the shaft means comprises an arm rotatively fixed with respect to the shaft means and extending generally radially therefrom, and structure mounted on the circle frame and slidingly receiving the outer end of the arm.

10. A control system for positioning the blade of a grading machine which comprises a vehicle'frame, a draw bar pivotally mounted at its forward end on the vehicle.

frame for angular movements relative thereto in respective longitudinal and transverse movement planes, theblade being carried adjacent the rearward end of the draw bar, and power means connected between the frame and the draw bar and actuable to drive the latter in its longitudinal angular movement; said control system comprising the combination of adrag link having one end pivotally mounted on the vehicle frame, means interconnecting the other end of the drag link with the draw bar at a point thereof that is spaced rearwardly from the pivotal mounting of the draw bar, electrical means operatively connected to the drag link and producing an electrical output in response to pivotal movement thereof, and means for actuating said power means under control of the electrical output.

11. A control system for positioning the blade of a grading machine which comprises a vehicle frame, a draw bar pivotally mounted at its forward end on the vehicle frame for angular movements relative thereto in respec tive longitudinal and transverse movement planes, the blade being carried adjacent the rearward end of the draw bar, and power means connected between the frame and the draw bar and actuable to drive the latter in its longi tudinal angular movement; said control system comprising the combination of electrical means having two mutually movable members and acting to produce an electrical output in response to mutual movement of the members, linkage means having one part connected to the frame and another part pivotally connected to the draw bar at a pivot point that is spaced rearwardly of the draw bar pivotal mounting, said pivot point and pivotal mounting defining a generally longitudinal axis, said linkage means deflecting in response to vertical swinging of said axis and the linkage deflection being independent of draw bar rotation about said axis, cou-' pling means connecting the electrical members to said linkage means to positively drive. the mutual movement of said members in accordance with linkage deflection, and means for actuating said power means under control of the electrical output.

12. A control system as defined in claim 11, and wherein said power means comprises two power lift mechanisms connected with the draw bar at respective laterally spaced connection points-thereof, each of said lift mechanisms being actuable in two opposite directions to raise and lower, respectively, the point of the draw bar to which it is connected, and said actuating means comprising two control members coupled to the respective lift mechanisms, each control member being movable in two opposite directions to produce corresponding actuation of the associated lift mechanism, and means for moving both control members in a common direction under control of the electrical output.

13. A blade control system for a grading machine which comprises a vehicle frame, a blade assembly including a blade and pivotally supported adjacent its forward end on the vehicle frame for angular movements relative thereto in respective longitudinal and transverse planes, two power lift mechanisms connected with the blade assembly at respective laterally spaced connection points thereof, each of said lift mechanisms being actuable in two opposite directions to raise and lower, respectively, the point of the blade assembly to which it is connected; said control system comprising the combina tion of first sensing means for producing a first electrical output responsive to variations in the transverse inclination of the blade assembly, second sensing means for producing a second electrical output responsive to variations in the longitudinal inclination of the blade assembly, actuating means for the respective lift mechanisms, each actuating means comprising armature means shiftable axially in two opposite directions, solenoid means comprising first and second solenoid windings energizable to shift the armature means in the respective directions, and coupling means connected between the armature means and the lift mechanism for actuating the latter in respective directions corresponding to the armature movement, means acting under control of the first electrical output to energize the two solenoid means difierentially, and means acting under control of the second electrical output to energize corresponding solenoids of both solenoid means References Cited in the file of this patent UNITED STATES PATENTS 1,936,518 McColm Nov. 21, 1933 2,502,217 Guibor Mar. 28, 1950 2,552,890 Eisler May 15, 1951 2,636,290 Bell Apr. 28, 1953 2,647,323 Johnson et al Aug. 4, 1953 2,755,721 Rusconi July 24, 1956 

